CVE-2025-66506

Name	CVE-2025-66506
Description	Fulcio is a free-to-use certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.3, function identity.extractIssuerURL splits (via a call to strings.Split) its argument (which is untrusted data) on periods. As a result, in the face of a malicious request with an (invalid) OIDC identity token in the payload containing many period characters, a call to extractIssuerURL incurs allocations to the tune of O(n) bytes (where n stands for the length of the function's argument), with a constant factor of about 16. This vulnerability is fixed in 1.8.3.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1122059

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
golang-github-sigstore-fulcio (PTS)	trixie	1.6.5-1	vulnerable
	forky, sid	1.7.1-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
golang-github-sigstore-fulcio	source	(unstable)	(unfixed)			1122059

Notes

[trixie] - golang-github-sigstore-fulcio <no-dsa> (Minor issue)
https://github.com/sigstore/fulcio/security/advisories/GHSA-f83f-xpx7-ffpw
Fixed by: https://github.com/sigstore/fulcio/commit/765a0e57608b9ef390e1eeeea8595b9054c63a5a (v1.8.3)